The invention pertains to a flareless tube connector for soft metal tubes wherein a compression nut inwardly radially deforms a compression sleeve and the material of the tube into metal-to-metal contact with a tube connector body nipple.
Compression fittings for soft metal tubes, such as those formed of copper or aluminum commonly employ a sleeve or bushing which slips over the end of the tubes and is compressed on the tube by means of a compression nut threaded upon the tube connector body to which the tube is to be attached. Such conventional fittings do not employ an internal support for the tube, and rely upon the metal-to-metal contact between the compression nut and bushing or sleeve with the outer surface of the tube to produce sealing.
While such known compression fittings have enjoyed success in many static installations, such as in plumbing and water distribution systems, such conventional compression fittings will often leak, or fail to maintain the assembly of the tube and the connector body, if relative movement between the tube and body takes place. Further, such conventional fittings will permit the tube to be axially withdrawn from the connector body under tension forces if a fitting is not properly assembled due to insufficient interconnection between the sleeve and the compression nut, or collapse of the tube.
Another deficiency with known compression fittings for use with soft metal tubes lies in the fact that the preferred torque on the compression nut is difficult to ascertain, and in the assembly of such fittings it is common to either under torque or over torque the compression nut, and in either instance fitting failure may occur.
It is an object of the invention to provide a permanent flareless tube connector for soft metal tubes utilizing a compression nut and deformable sleeve wherein tightening of the compression nut forms a permanent metal-to-metal seal between the tube and the tube connector body.
A further object of the invention is to provide a flareless tube connector for soft metal tubes wherein a compression nut is utilized to inwardly deform a compression sleeve upon an internally supported tube and the completion of assembly of the compression nut on the tube connector body is readily discernable whereby over torquing and under torquing is eliminated, and the operator is aware of the proper assembly being completed.
Yet another object of the invention is to provide a permanent flareless connector for soft metal tubes utilizing a nipple located upon a tube connector body over which the tube is inserted, and wherein a compression nut deforms an annular compression sleeve upon the tube to deform the tube material onto mechanical sealing and gripping surfaces defined on the tube connector body nipple.
Another object of the invention is to provide a permanent flareless connector for soft metal tubes utilizing a compression nut and radially deformable sleeve wherein the sleeve configuration aids in its deformation and is fool proof in its assembly upon the tube.
Additionally, a further object of the invention is to produce a permanent flareless tube connector for soft metal tubes utilizing a tube connector body having a nipple received within the tube wherein the nipple supports the tube against side loading forces such that the fitting is capable of resisting high lateral forces without leaking resulting in a fitting capable of installation in high vibration and abuse environments not suitable for conventional compression tube fittings.
In the practice of the invention a tube connector body includes an annular nipple adapted to be received within the end of a soft metal tube. The body also includes exterior threads for receiving a compression nut and a radial abutment surface is defined inwardly of the threads against which the compression nut bottoms at the completion of assembly.
The connector body further includes an abutment surface adjacent the nipple against which the tube end abuts during initial assembly and an annular compression sleeve also engages this abutment surface during threading of the compression nut located upon the tube as it engages the threads of the body. A cam surface upon the compression nut radially inwardly deforms a portion of the compression sleeve against the tube and deforms the tube material into an annular groove defined upon the body nipple. The nipple groove includes a shoulder surface against which the deformed tube materail engages which prevents axial withdrawal of the tube on the nipple and a metal-to-metal seal exists between the deformed tube material and the nipple.
The portion of the compression sleeve engaged by the compression nut cam surface is of a greater radial dimension than a hinging portion defined upon the sleeve to facilitate inward sleeve deformation against the tube, and in the preferred sleeve embodiment a greater wall thickness is defined upon the sleeve adjacent each of its axial ends as compared with the sleeve central wall thickness which is of a lesser radial dimension to facilitate sleeve deformation. The symmetrical sleeve configuration permits the sleeve to properly function regardless of which end thereof is initially inserted on the tube prior to assembly of the connector body and compression nut.